@article{ref1,
title="Independence of channels in colour contrast perception",
journal="Nature",
year="1975",
author="Ellis, B. and Burrell, G. J. and Wharf, J. H. and Hawkins, T. D.",
volume="254",
number="5502",
pages="691-692",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0028-0836",
doi="",
url="http://dx.doi.org/"
}